INTRODUCTION
Consuming cigarettes or smoking is a common factor that leads to chronic obstructive pulmonary disease1, lung cancer2, and other malignant tumor diseases3. Nicotine dependence has been defined as a mental disorder4 with withdrawal symptoms like other drugs. There are many behavioral factors involved in smoking, and each smoker has a different lifestyle, and hence smoking can occur across a variety of environments. We have summarized a unique environment from previous literature that explains clearly why smoking and behaviors coexist: the progression of mental activities. It has the same properties that increase dopamine release and dopamine consumption5,6. Ex-smokers or never-smokers who work overtime are more likely to become smokers because of increased stress and exhaustion7,8. Gambling and playing video games are two environmental motivational stimuli which, combined with smoking or other addictive substances, may increase dopamine in the nucleus accumbens6,9,10. It is customary in China for people to attend mental activities on weekends or during the evening hours after dinner. However, few studies have explained the relationship between mental activities after dinner, which can stimulate the mind, and daily consumption of cigarettes as well as nicotine dependence.
Chinese smokers like drinking tea while working or engaging in mental activities. The main component of tea is caffeine, but it is not completely consistent with the caffeine component in coffee beverages11. The relationship between smoking and drinking tea has not been explained specifically in previous research12,13.
Furthermore, there is limited research comparing the number of cigarettes smoked and nicotine dependence with smokers’ habits of drinking tea and engaging in mental activities after dinner. Therefore, we collected smokers’ information and behaviors from clinic records. To clarify whether smokers with drinking tea, mental activities after dinner or these two behaviors in combination, consume more cigarettes or are more nicotine dependent, the daily cigarettes consumed and the Fagerström scores were used as indexes of smoking severity.
METHODS
Patients and information collection
From June 2009 to August 2020, 438 smokers were retrospectively enrolled at The Affiliated Hospital of Medical School, Ningbo University. As the smokers came to our clinic for counseling and treatment, the doctor recorded their habits and all other information. Our study collected and analyzed these data, retrospectively. The study was approved by the Ethics Committee of the Affiliated Hospital of Medical School, Ningbo University (Ningbo, China). The methods used were in accordance with NCCN Clinical Practice Guidelines in Oncology of Smoking Cessation14.
Study design
Age, gender, Body Mass Index (BMI, kg/m2), and the number of cigarettes consumed per day were recorded. Smokers with FTND <1 or with a diagnosis of a mental disorder were excluded from the study. In addition, the FTND scores were used to evaluate the level of nicotine dependence15,16. The following behaviors were observed: 1) drinking tea; and 2) participating in mental activities after dinner before sleeping for at least one hour (including gambling10, overtime work7, and playing video games17).
Smokers who smoked during the period of mental activities after dinner before sleep were included in the study. Since the plasma half-life of nicotine is 2 hours18, we did not record the number and duration of cigarettes smoked. Among patients with tobacco addiction, at least three of the following six criteria must be met19-21: 1) craving, or a strong desire or urge to use tobacco; 2) persistent desire or unsuccessful efforts to cut down or control tobacco use; 3) experiencing tobacco withdrawal symptoms (such as irritability, frustration, anger, anxiety, difficulty concentrating, increased appetite, restlessness, insomnia) after abrupt cessation of tobacco use, or reduction in the amount of tobacco used; 4) tolerance, defined as the need for markedly increased amounts of tobacco to achieve the desired effect; 5) given up or reduced important social, occupational, or recreational activities because of tobacco use; and 6) continued tobacco use, despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by tobacco. We firstly excluded patients without all these conditions because they were deemed to be not addicted to tobacco. None of the patients with FTND <1 met these conditions.
Smokers were divided into four groups according to behaviors: 1) no drinking tea and no mental activities after dinner group; 2) only drinking tea; 3) only mental activities after dinner; and 4) combination behaviors (drinking tea and mental activities after dinner together).
Statistical analysis
Fisher’s exact test was used to calculate the gender distribution. Mean ± standard deviation (SD) and t-test were used for age, BMI and cigarette consumption. FTND scores are presented as median (Q1, Q3) and were calculated by Mann-Whitney U test. Cigarette consumption and FTND score of tea group, mental activities after dinner group, combination behaviors group, were all compared with no tea no mental activities group, respectively. IBM SPSS Statistics 21.0 was used for all statistical analyses. A value of p<0.05 was judged as statistical different. There is no comparison between the groups, so the alpha value does not need to be corrected.
RESULTS
The age, BMI, and gender distribution of smokers in four groups were not significantly different. Table 1 indicates that only drinking tea or engaging in mental activities after dinner was not related with the number of cigarettes per day (22.20 ± 10.143 vs 23.49 ± 11.966, p=0.362; 22.20 ± 10.143 vs 22.66 ± 1.192, p=0.750) or FTND scores [6.0 (4.0; 7.0) vs 6.0 (4.0; 7.75), p=0.941; 6.0 (4.0; 7.0) vs 6.0 (4.25; 7.75), p=0.980]. Patients who combine drinking tea with mental activities after dinner were found to smoke more (22.20 ± 10.143 vs 30.75 ± 17.264, p<0.0001) and display higher levels of nicotine dependence [6.0 (4.0; 7.0) vs 7.0 (5.0; 8.0), p=0.015].
Table 1
Cigarette consumption and nicotine dependence in different groups
| Characteristics | No drinking tea or mental activities after dinner (n=124) | Only drinking tea (n=124) | p | Only mental activities after dinner (n=97) | p | Drinking tea and mental activities after dinner (n=93) | p |
|---|---|---|---|---|---|---|---|
| Age (years), mean ± SD | 43.54 ± 12.142 | 47.39 ± 10.336 | 0.008 | 39.72 ± 10.925 | 0.016 | 43.45 ± 11.222 | 0.089 |
| Gender, n | |||||||
| Male | 114 | 115 | 1 | 88 | 0.811 | 90 | 0.16 |
| Female | 10 | 9 | 9 | 3 | |||
| BMI (kg/m²), mean ± SD | 24.183 ± 9.291 | 23.697 ± 2.827 | 0.578 | 23.019 ± 3.093 | 0.238 | 22.708 ± 3.852 | 0.151 |
| Daily cigarette consumption, mean ± SD | 22.20 ± 10.143 | 23.49 ± 11.966 | 0.361 | 22.66 ± 1.192 | 0.75 | 30.75 ± 17.264 | <0.0001* |
| FTND score, median (Q1, Q3) | 6.0 (4.0; 7.0) | 6.0 (4.0; 7.75) | 0.941 | 6.0 (4.25; 7.0) | 0.98 | 7.0 (5.0; 8.0) | 0.015* |
* p<0.05 was considered as statistical difference. Because there is no comparison between groups, there is no need to correct the alpha value. Cigarette consumption was calculated by t-test analysis in tea group, mental activities after dinner group, tea and mental activities after dinner group. All compared with no tea no mental activities group, respectively. FTND score was calculated by Mann-Whitney U test in tea group, mental activities after dinner group, tea and mental activities after dinner group. All compared with no tea no mental activities group, respectively.
DISCUSSION
Several malignant diseases are associated with smoking3, and smoking is an increasingly significant public health issue worldwide. Smokers often engage in mental activities after dinner in China, where it is common to drink tea while smoking22. According to the characteristics of smokers in smoking cessation clinics, mental activities and drinking tea after dinner are long-term behaviors and cumulative processes. We cannot track these activities in a prospective manner. The majority of people do not experience these factors at the same time. There was a statistically significant difference in the number of cigarettes smoked per day among people who did not engage in mental activities after eating dinner and did not consume caffeinated beverages, based on previous research13,23,24. On the basis of these findings, we set out to investigate the effect of drinking tea and engaging in mental activity after dinner on smoking. In our study, smokers with combined behaviors (drinking tea and participating in mental activities after dinner) smoked more and had higher nicotine dependence scores than smokers drinking tea or participating in mental activities alone.
Chinese smokers prefer green tea, and caffeine’s constituents function in tea differently from those in coffee. Green tea requires a long infusion period since Chinese smokers prefer to steep leaves continuously in cups by adding boiling water repeatedly until the leaves no longer have a taste. In this way, the caffeine contained in green tea is fully released into the water. Caffeine consumption is higher in Chinese smokers22. The main constituents of tea are polyphenols, catechins, theanine, proteins, enzymes, caffeine, carbohydrates, and inorganic compounds11. Despite the fact that cups of coffee generally contain 1.4 to 3.4 times more caffeine than cups of tea25, drinking tea every day provides a chronic caffeine exposure environment conducive to shaping and maintaining tobacco addiction24. Additionally, the caffeine in tea has a faster response time than theanine26, which explains why some smokers continue to crave cigarettes after drinking tea. Drinking caffeine beverages increases anxiety levels27,28 so smokers use nicotine to relieve anxiety by providing a calming effect28,29.
However, drinking tea or caffeine beverages cannot take full responsibility for the number of cigarettes smoked per day13. Although smokers drink more coffee than non-smokers or ex-smokers, not every smoker drinks coffee, or tea, and smokes at the same time13,24. The behavior of engaging in mental activities after dinner, which increases dopamine consumption in smokers, increases the risk of smoking more and has been associated with a higher FTND score7,10,17,30,31. Yet, no research has been able to demonstrate an increase in cigarettes or FTND scores in these smokers. According to our data, patients in only the mental activities group smoke the same number of cigarettes per day. It is possible that the results are due to the choice of smokers as the control group (no tea, no mental activities) rather than non-smokers or ex-smokers. As a results, drinking only tea will not increase cigarette consumption or FTND level, implying the same conclusion from data.
The data critically indicate that smokers with behaviors such as drinking tea and engaging in mental activities after dinner smoke more and score higher on the FTND scale. On the one hand, Chinese often work during their spare time or on the weekends, especially after dinner and during the evening. Smokers who work overtime may be stressed7. Stress is the third variable when smokers drink coffee during mental activities8,32. Perceived stress has been strongly associated with nicotine withdrawal symptomatology and may exacerbate nicotine withdrawal symptoms33. Conditions, caffeine intake, or the combination of stress and condition, contribute to the increase in the number of cigarettes consumed13. Alternatively, mental activities after dinner may occur in conjunction with smoking and drinking tea. There are two reasons for this. First, a brief outline of the role of dopamine and its deficiencies is as follows: dopamine helps to get rid of tiredness after all day work34; dopamine also helps focus attention if the brain is not well rested34; and dopamine deficiency occurs during mental activities due to inverted-U-shaped (dopamine was consumed by the brain) dopamine actions on memory and cognitive control5, especially in drug addicts and smokers35. Second, are the choices of dopamine supplementation during mental activities, as tea is available as easy as coffee in China; the sedative effect of dopamine produced by nicotine would relieve the anxiety24 and stress caused by the caffeine found in tea24,28 and the mental activities. Furthermore, the co-production of dopamine by nicotine and caffeine at the same time could help focus greater attention during mental activities24. As a result, smokers who consume tea and engage in mental activities after dinner may have a higher level of nicotine dependence and more cigarettes consumed per day.
Limitations
There are some limitations to our research. First, we were unable to compile a detailed record of mental activities along with an assessment of patient stress and anxiety, and hence we were unable to explore more additional traits. Second, further information on the type of tea, amount of tea consumed, and the manner in which smokers in China drink tea was not recorded. Third, lifestyle behaviors may have interacted effects with each other, which need to be explained more specifically in future studies such as whether smoking would lead to drinking tea. Fourth, the information we collected was from smokers who attended smoking cessation clinics, and all of them had obvious signs of physical addiction to smoking. However, the proportion of people quitting smoking in China remains low, and there is not much awareness of the benefits of quitting36. There are many environmental factors that contribute to increased smoking, but some of these factors are psychological rather than physical. Although there are many factors that contribute to smoking, our study is only a preliminary summary of these patient characteristics. Further research is needed with studies of more appropriate design.
